Energy extraction system

ABSTRACT

An energy extraction system for a rotational surface including a drive mechanism having a rotational axis and configured to rotatably couple to the rotational surface and an energy extraction mechanism coupled to the drive mechanism. The drive mechanism includes a cam rotatable about the rotational axis and an eccentric mass coupled to the cam that offsets a center of mass of the drive mechanism from the rotational axis, the eccentric mass cooperatively formed by a first and a second section, the eccentric mass operable between a connected mode wherein the first and second sections are adjacent and a disconnected mode wherein the first and second sections are separated. The energy extraction mechanism is connected to the cam and is statically coupled to the rotating surface, wherein the energy extraction mechanism configured to extract energy from relative rotation between the energy extraction mechanism and the cam.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 14/019,899, filed 6 Sep. 2013, which is a continuation of U.S.patent application Ser. No. 13/797,811, filed 12 Mar. 2013, which claimsthe benefit of U.S. Provisional Application No. 61/613,406 filed 20 Mar.2012, U.S. Provisional Application No. 61/637,206 filed 23 Apr. 2012,and U.S. Provisional Application No. 61/672,223 filed 16 Jul. 2012,which are incorporated in its entirety by this reference.

TECHNICAL FIELD

This invention relates generally to the passive energy extraction field,and more specifically to a new and useful stabilizer in the passiveenergy extraction field.

BACKGROUND

In many applications, it is often desirable to passively extract energyfrom rotating systems, such as tires, windmills, or waterwheels. Someconventional systems harvest this energy by inducing relative motionbetween the rotating system and a stationary system having a center ofgravity offset from the rotational axis. Examples of such systems caninclude pendulum systems or hanging mass systems (eccentric masssystems). However, conventional eccentric-mass driven systems, such aspendulum systems, experience instabilities when the rotating surface towhich the eccentric mass is coupled receives outside stimulus (e.g.vibrations, bumps, rotational oscillations, etc.), particularly when therotating surface rotates at the excitation frequency for the giveneccentric mass. In response to an outside stimulus, the eccentric masstends to rotate with the system, resulting in radial oscillations thatcan be detrimental to the energy extraction system or to the rotatingsurface to which the energy extraction system is coupled.

Thus, there is a need in the energy extraction field to create a new anduseful energy extraction system having a stabilizing mechanism.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic representation of an energy extraction system fora rotating surface.

FIG. 2 is a schematic representation of a pump system utilizing a camand eccentric mass.

FIGS. 3A and 3B are schematic representations of a variation of thestabilizing mechanism in the cohesive state and the separated state,respectively.

FIGS. 4A and 4B are schematic representation of a second variation ofthe stabilizing mechanism in the cohesive state and the separated state,respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiments of the inventionis not intended to limit the invention to these preferred embodiments,but rather to enable any person skilled in the art to make and use thisinvention.

As shown in FIG. 1, the energy extraction system 10 includes anextraction mechanism 100 and a drive mechanism 200 rotatably coupled tothe extraction mechanism 100, the drive mechanism 200 including a cam220 coupled to an eccentric mass 240. The energy extraction system 10preferably functions to extract energy from relative motion between theenergy extraction mechanism 100 and the drive mechanism 200. The energyextraction system 10 preferably couples to a rotating surface 20,wherein the extraction mechanism 100 is preferably statically coupled tothe rotating surface 20 and wherein the eccentric mass 240 retains thecam angular position relative to a gravity vector while the extractionmechanism rotates relative to the drive mechanism 200 (e.g., with therotating surface 20). The energy extraction system 10 is preferablypassively controlled, but can alternatively be actively controlled,wherein the system further includes a power source, a plurality ofsensors, and a controller that controls valve operation based on sensormeasurements. The extraction mechanism 100 is preferably coupled to anenergy storage device 30, such as a battery (e.g., wherein theextraction mechanism 100 extracts electrical power) or a fluid reservoir(e.g., wherein the extraction mechanism 100 extracts linear force).

The energy extraction system 10 is preferably couplable to a surfacethat rotates relative to a gravity vector (rotating surface 20). Therotating surface 20 is preferably a wheel of a vehicle, more preferablya truck, but can alternatively be any suitable rotating system, such asa windmill, waterwheel, or any other suitable rotating surface 20.

The extraction mechanism 100 of the energy extraction system 10functions to extract energy from the relative motion between the cam 220and the extraction mechanism 100. The extraction mechanism 100 ispreferably configured to statically couple to and rotate with therotating surface 20, but can alternatively be otherwise coupled to therotating surface 20. The extraction mechanism 100 preferably rotatesalong an arcuate path exterior the cam 220, but can alternatively rotatealong an arcuate path within the cam perimeters. The arcuate path of theextraction mechanism 100 is preferably centered about the rotationalaxis 202 of the drive mechanism 200, but can alternatively be otherwisepositioned. The energy extraction system 10 preferably includes at leastone extraction mechanism 100, but can alternatively include multipleextraction mechanisms, wherein the multiple extraction mechanisms arepreferably substantially evenly distributed about the rotational axis202 of the drive mechanism 200 at substantially the same radialdistance, but can alternatively be otherwise positioned.

In a first variation of the energy extraction system 10 as shown in FIG.2, the extraction mechanism 100 includes a pump 120 and a forcetranslator 140. The pump 120 is preferably a positive displacement pump,but can alternatively be any other suitable pump. The positivedisplacement pump 120 preferably includes a pump cavity and an actuatingelement that forms a fluid impermeable seal against the pump cavity andtranslates within the pump cavity to displace fluid. The positivedisplacement pump 120 is preferably a reciprocating pump (wherein a pumpchamber is the pump cavity and a reciprocating element is the actuatingelement), but can alternatively be a peristaltic pump (wherein a grooveis the pump cavity and a diaphragm or tube is the actuating element),such as that disclosed in U.S. application Ser. No. 13/187,949 filed 21Jul. 2011, incorporated herein in its entirety by this reference, or anyother suitable positive displacement pump. The reciprocating pump ispreferably a piston pump, but can alternatively be a diaphragm pump, adiaphragm pump with a piston coupled to the diaphragm, or any othersuitable reciprocating pump. The pump 120 is preferably coupled to thedrive mechanism 200 a fixed radial distance away from the rotationalaxis 202, but can alternatively be coupled to the drive mechanism anadjustable radial distance away from the rotational axis 202, be coupledto the drive mechanism in the same plane or a different plane as thecam, or be coupled to the drive mechanism in any other suitableposition. The pump 120 preferably includes a fluid inlet connected to afirst reservoir and a fluid outlet connected to a second reservoir,wherein the pump 120 preferably pumps fluid from the first reservoir tothe second reservoir. The pump 120 can additionally function topressurize the fluid egressed into the second reservoir. The firstreservoir is preferably the ambient environment, but can alternativelybe a housing encompassing the drive mechanism 200 and the extractionmechanism 100 or any other suitable fluid source. The second reservoiris preferably a tire interior, but can alternatively be any othersuitable fluid reservoir. The fluid inlet preferably includes an inletvalve that is in an open mode when the pressure within the pump 120 issubstantially equal to or less than the pressure of the first reservoirand in a closed mode when the pressure within the pump 120 exceeds thepressure of the first reservoir, but can alternatively not include avalve or include any suitable number of valves. The fluid outletpreferably includes an outlet valve that is in an open mode when thepressure within the pump 120 is substantially equal to or more than thepressure of the second reservoir and in a closed mode when the pressurewithin the pump 120 is less than the pressure of the second reservoir,but can alternatively not include a valve or include any suitable numberof valves. The inlet and outlet valves are preferably one-way passivevalves, but can alternatively be active valves or any other suitablevalves.

The force translator 140 functions to connect the pump 120 to the drivemechanism 200. More preferably, the force translator 140 functions toconnect the actuating element to the cam 220, wherein the forcetranslator 140 translates relative motion between the drive mechanism200 and the pump 120 into a variable occluding force. The forcetranslator 140 preferably applies a force in a radially outwarddirection from the rotational axis 202, but can alternatively apply aforce in a radially inward direction, in a direction substantiallyparallel to the rotational axis 202, in a direction at an angle to therotational axis 202, or in any other suitable direction. In a firstalternative of the pump 120, the force translator 140 includes aplanetary roller that rolls about an interior or exterior arcuatesurface of the cam 220 (e.g., as disclosed in U.S. application Ser. No.13/187,949, but alternatively any other suitable system can be used).This alternative is preferably used when the pump 120 is a peristalticpump, but can alternatively be used for any other suitable pump system.In a second alternative of the pump 120, the force translator 140 is aroller with a rotational axis 202 that is statically fixed to a point onthe pump cavity, more preferably to the actuation axis of the pump 120.This alternative is preferably used with a reciprocating pump, but canalternatively be used with any other suitable pump 120. The roller ispreferably in non-slip contact with a bearing surface of the cam 220,wherein the cam 220 preferably has a bearing surface with a varyingcurvature, such that the roller applies a variable force to theactuating element as the roller rolls over the variable bearing surface.The roller slides relative to the actuating element, but canalternatively be in contact with the actuating element in any othersuitable manner. In a third alternative of the pump 120, the forcetranslator 140 includes a linkage rotatably connected to a fixed pointon the cam 220 and rotatably coupled to the actuating element, whereinthe linkage preferably actuates the actuating element through acompression stroke and a recovery stroke as the fixed point nears andretreats from the pump cavity position, respectively. Alternatively, thelinkage can actuate the actuating element through the compression strokeand recovery stroke as the fixed point retreats from and nears the pumpcavity, respectively. The linkage preferably includes a single link, butcan alternatively include two or more links rotatably connected at therespective ends. However, any other suitable force translator 140 can beused.

In a second variation of the energy extraction system 10, the extractionmechanism 100 includes an electromagnetic field and a conductiveelement. The motion of the conductive element through the appliedelectromagnetic field preferably generates a current, which ispreferably subsequently stored or harvested by a load. The load ispreferably electrically connected to the conductive element. Theelectromagnetic field is preferably an electric field, which ispreferably generated by a first and a second electrode, wherein thefirst electrode is preferably held at an electric potential differentfrom the second electrode. Alternatively, the electromagnetic field canbe a magnetic field generated by one or more magnets. The conductiveelement can be a wire, wound wires, a rotor, a magnet, or any othersuitable conductive element. The electric field preferably rotates withthe rotating surface 20 (wherein the electrodes are statically coupledto the rotating surface 20), and the conductive element is preferablylocated on the cam 220. Alternatively, the electric field can begenerated by the cam 220 (e.g., wherein the first electrode is locatedon the cam 220 and the second electrode located on a surface that isstatic relative to a gravity vector, wherein the first and secondelectrodes are located on opposing sides of the cam 220, wherein theextraction mechanism 100 is positioned within the cam perimeter, etc.),wherein the conductive element preferably rotates with the rotatingsurface 20.

In a third variation of the energy extraction system 10, the extractionmechanism 100 includes a force translator 140, similar to the onedescribed above but alternatively can be any other suitable forcetranslator 140, and a piezoelectric element that transforms the radialforce applied by the force translator 140 into electricity.

However, any other suitable extraction mechanism 100 that extractsenergy from the relative motion between the rotating surface 20 and thedrive mechanism 200 can be used.

The drive mechanism 200 of the energy extraction system 10 functions toinduce relative motion between the extraction mechanism 100 and thedrive mechanism 200. The drive mechanism 200 preferably includes the cam220 and the eccentric mass 240. The drive mechanism 200 includes arotational axis 202 about which the drive mechanism 200 rotates relativeto the extraction mechanism 100 (conversely, about which the extractionmechanism rotates relative to the drive mechanism 200). The rotationalaxis 202 of the drive mechanism 200 is preferably the rotational axis ofthe cam 220, but can alternatively be the rotational axis of theeccentric mass 240, the rotational axis about which the extractionmechanism rotates, or any other suitable rotational axis. The energyextraction system 10 is preferably configured such that the rotationalaxis of the drive mechanism 200 is substantially aligned with therotational axis of the rotating surface 20 when the energy extractionsystem 10 is coupled to the rotating surface 20, but the energyextraction system 10 can alternatively be configured such that therotational axis of the drive mechanism 200 is offset from the rotationalaxis 202 of the rotating surface 20. The drive mechanism 200additionally includes a center of mass, determined from the mass andpositions of the cam 220 and the eccentric mass 240. The eccentric mass240 is preferably coupled to the cam 220 such that the center of mass ofthe drive mechanism 200 is offset from the rotational axis 202 of thedrive mechanism 200.

The cam 220 of the drive mechanism 200 functions to interface with theextraction mechanism 100. In a first variation, the cam 220 includes anarcuate bearing surface that interfaces with the extraction mechanism100. More preferably, the arcuate bearing surface interfaces with aroller force translator 140 of the extraction mechanism 100. In onealternative as shown in FIG. 2, the cam 220 includes a bearing surfacewith a variable curvature that controls the magnitude of thesubstantially linear, radial force applied to the extraction mechanism100. The cam 220 preferably functions to provide a substantiallyconstant torque against the reciprocating element throughout thecompression stroke, but can alternatively provide a variable torqueagainst the reciprocating element throughout the compression or recoverystrokes. The cam 220 preferably includes a bearing surface, wherein theprofile of the bearing surface preferably controls the magnitude of theforce throughout the compression stroke. The bearing surface ispreferably continuous, but can alternatively be discontinuous. Thebearing surface is preferably defined on the exterior of the cam 220(exterior bearing surface or outer bearing surface) but canalternatively be defined within the interior of the cam 220 (interiorbearing surface or inner bearing surface), wherein the bearing surfacedefines a lumen within the cam 220. The bearing surface preferablyarcuate, and preferably has a non-uniform curvature (e.g. an oblong or areniform profile). Alternatively, the bearing surface can have a uniformcurvature (e.g. a circular profile), an angular profile, or any othersuitable profile. The bearing surface preferably includes a compressionportion and a recovery portion, corresponding to the compression strokeand the recovery stroke of the extraction mechanism 100, respectively.The compression portion is preferably continuous with the recoverysection, but can alternatively be discontinuous. The bearing surfacepreferably has a first section having a high curvature (preferablypositive curvature or convex but alternatively negative curvature orconcave) adjacent a second section having low curvature (e.g.,substantially flat or having negative curvature compared to the firstsection). The bearing surface preferably additionally includes a thirdsection connecting the first and second sections, wherein the thirdsection preferably provides a substantially smooth transition betweenthe first and second sections by having a low curvature adjacent thefirst section and a high curvature adjacent the second section. Thecompression portion preferably begins at the end of the second sectiondistal the first section, extends along the third section, and ends atthe apex of the first section. The compression portion is preferablyconvex (e.g., when the bearing surface is an external bearing surface),but can alternatively be concave. The apex of the first sectionpreferably corresponds to the top of the compression stroke (compressedposition). The recovery portion preferably begins at the apex of thefirst section, extends along the second section, and ends at the end ofthe second section distal the first section. The recovery portion ispreferably substantially flat or concave (e.g., when the bearing surfaceis an external bearing surface), but can alternatively be convex. Theend of the second section preferably corresponds to the bottom of therecovery stroke (recovered position). The slope of the compressionportion is preferably less than 30 degrees, but can alternatively haveany suitable angle. When a roller is used as the force translator 140,the curvature of the bearing surface is preferably at least three timeslarger than the roller curvature or roller diameter, but canalternatively be larger or smaller. However, the bearing surface canhave any suitable profile. The cam 220 is preferably substantiallyplanar with the bearing surface defined along the side of the cam, in aplane normal to the rotational axis of the cam (e.g., normal the broadface of the cam). The bearing surface is preferably defined along theentirety of the cam side, but can alternatively be defined along aportion of the cam side. The generated pump force is preferably directedradially outward of the rotational axis 202, more preferably along aplane normal to the rotational axis 202. Alternatively, the cam 220 canhave a rounded or otherwise profiled edge segment (transition betweenthe cam broad face and the cam side), wherein the bearing surface caninclude the profiled edge. Alternatively, the arcuate surface is definedby a face of the cam 220 parallel to the rotational axis of the cam 220,wherein the generated pump force can be directed at any suitable anglerelative to the rotational axis 202, varying from parallel to therotational axis to normal to the rotational axis. The compressionportion preferably encompasses the majority of the cam profile, but canalternatively encompass half the cam profile or a small portion of thecam profile. In one variation, the compression portion covers 315degrees of the cam profile, while the recovery portion covers 45 degreesof the cam profile. However, the compression and recovery portions cancover any other suitable proportion of the cam profile.

In another alternative, the cam 220 is a disk with a substantiallycircular profile. In yet another alternative, the cam 220 is a spheresegment or catenoid, wherein the bearing surface is preferably definedalong the arcuate surface. In yet another alternative, the cam 220 is abearing rotatably coupled about an axle statically coupled to therotating surface 20. The cam 220 can alternatively have any othersuitable form factor or configuration.

The eccentric mass 240 (hanging mass) of the drive mechanism 200functions to offset the center of mass of the drive mechanism 200 fromthe rotational axis 202 of the drive mechanism 200. This offset canfunction to substantially retain the angular position of the cam 220relative to a gravity vector, thereby engendering relative motionbetween the drive mechanism 200 and the extraction mechanism 100statically coupled to the rotating surface 20 (that rotates relative tothe gravity vector). The eccentric mass 240 is preferably asubstantially homogenous piece, but can alternatively be heterogeneous.The eccentric mass 240 is preferably a distributed mass (e.g., extendsalong a substantial portion of an arc centered about the rotational axis202, as shown in FIG. 2), but can alternatively be a point mass. Theeccentric mass 240 is preferably curved, but can alternatively besubstantially flat, angled, or have other suitable shape. The radius ofthe eccentric mass curvature is preferably maximized, such that theeccentric mass 240 traces an arcuate section of the energy extractionsystem perimeter. However, the eccentric mass 240 can have any othersuitable curvature. The eccentric mass 240 preferably extends at least90 degrees about the rotational axis 202 of the drive mechanism 200,more preferably 180 degrees about the rotational axis 202, but canextend more or less than 180 degrees about the rotational axis 202. Theeccentric mass 240 preferably has substantially more mass than the cam220, but can alternatively have a substantially similar mass or asmaller mass. The eccentric mass 240 preferably imparts 2 in-lb (0.225Nm) of torque on the cam 220, but can alternatively impart more or lesstorque.

The eccentric mass 240 is preferably a separate piece from the cam 220,and is preferably coupled to the cam 220 by a mass couple 260. Theeccentric mass 240 can be statically coupled to the cam 220 or rotatablycoupled to the cam 220. In the variation wherein the eccentric mass 240is statically coupled to the cam 220, the eccentric mass 240 can becoupled to the cam 220 at the rotational axis of the cam 220, at therotational axis 202 of the drive mechanism 200, offset from therotational axis of the cam 220, or at any other suitable portion of thecam 220. The eccentric mass 240 can be permanently connected to the cam220. Alternatively, the eccentric mass 240 can be transiently connected(removably coupled) to the cam 220, wherein the eccentric mass 240 canbe operable between a coupled mode wherein the eccentric mass 240 iscoupled to the cam 220 and a decoupled mode wherein the eccentric mass240 is rotatably coupled to the cam 220 or otherwise decoupled fromangular cam 220 motion. The mass couple 260 preferably has a high momentof inertia, but can alternatively have a low moment of inertia. The masscouple 260 is preferably a disk, but can alternatively be a lever arm,plate, or any other suitable connection. The mass couple 260 preferablycouples to the broad face of the cam 220, but can alternatively coupleto the edge of the cam 220, along the exterior bearing surface of thecam 220, to the interior bearing surface of the cam 220, to an axleextending from the cam 220 (wherein the cam 220 can be statically fixedto or rotatably mounted to the axle), or to any other suitable portionof the cam 220. The mass couple 260 can couple to the cam 220 byfriction, by a transient coupling mechanism (e.g., complimentaryelectric or permanent magnets located on the cam 220 and mass couple260, a piston, a pin and groove mechanism, etc.), by bearings, or by anyother suitable coupling means.

The energy extraction system 10 can additionally include a stabilizingmechanism 300 that functions to reduce rotational surface imbalance whenthe eccentric mass 240 becomes excited (e.g., begins spinning) when theenergy extraction system 10 receives a destabilizing force and theeccentric mass becomes excited (e.g., rotates about the axis of rotationfor the system). Eccentric mass excitation can destabilize therotational surface, potentially leading to catastrophic energyextraction system and/or rotating surface damage. The inventors havediscovered that the system can be stabilized at the excitation frequencyby using an eccentric mass 240 that is collectively formed from multiplesections (e.g., wherein the eccentric mass 240 is the stabilizingmechanism 300). When the rotating system rotates at frequencies lessthan the excitation frequency and/or does not receive a destabilizingforce, the eccentric mass 240 is preferably in a cohesive state(connected mode), with all composite sections of the eccentric mass 240substantially adjacent (e.g., as shown in FIGS. 3A and 4A). When theeccentric mass 240 begins to spin, the composite sections of theeccentric mass 240 separate in opposing directions and spin about theaxis of rotation, eventually settling at the separated state(disconnected mode, e.g., as shown in FIGS. 3B and 4B). This isparticularly useful when system oscillations cause the eccentric mass240 (and mass couple 260) to spin about the shaft; the centrifugalforces cause the sections of the split eccentric mass to separate and beevenly distributed about the axis of system rotation. Not only does thishave the effect of dynamically balancing the system and/or rotatingsurface 20, but the even distribution of the eccentric mass 240 withinthe system also halts system pumping. The latter effect may allow theeccentric mass 240 to additionally function as a control mechanism,wherein the eccentric mass resonant frequency may be tailored such thatpumping is ceased when a predetermined rotation speed or vibrationfrequency is reached. The multiple sections are preferably eachpositioned the same radial distance away from the rotational axis 202(the eccentric mass 240 is radially divided into multiple sections,wherein the multiple sections have different angular positions), but canalternatively be positioned at different radial distances (e.g., whereinthe multiple sections have substantially similar angular positions,etc.). The multiple sections preferably share a common plane, whereinthe common plane is preferably substantially parallel to the rotationalsurface. The multiple sections can collectively form an arc, centeredabout the rotational axis 202, that intersects the common plane (e.g.,the multiple sections are adjacent along an arc), form a block thatintersects the common plane, or collectively form any other suitablestructure. Alternatively, the multiple sections can be stacked along thethicknesses of the sections, wherein the section thicknesses arepreferably parallel to the rotational axis 202. The multiple sectionspreferably have substantially the same mass, but can alternatively havedifferent masses. The center of mass for each eccentric mass section ispreferably offset from the mass couple connection point for eacheccentric mass section, and is preferably arranged proximal an adjacenteccentric mass section. In operation, the eccentric mass sectionsseparate until the centers of mass of the eccentric mass sections opposeeach other across the axis of rotation.

When the eccentric mass 240 is cooperatively formed by multiplesections, the mass couple 260 preferably also includes multiplesections, wherein each mass couple section statically couples to aneccentric mass section. The mass couple sections are preferablyrotatably coupled to the cam 220, but can alternatively be staticallycoupled to the cam 220. Each mass couple section is preferably rotatablycoupled to the remaining mass couple sections, but can alternatively bestatically coupled to one or more of the remaining mass couple sections.In one variation as shown in FIGS. 4A and 4B, the end of each masscouple section opposing the eccentric mass section is rotatably coupledto the housing. The angular positions of mass couple section ends arepreferably static relative to the housing, wherein the mass couplesection ends are preferably equally distributed about the axis ofrotation. In another variation, the end of the each mass couple sectionopposing the eccentric mass section includes a bearing, wherein thebearing is slidably engaged within a circumferential groove 221statically coupled to the cam 220 and encircling the rotational axis202. When the rotation frequency of the rotating surface 20 is below orabove the excitation frequency for the cooperatively defined eccentricmass 240, the centrifugal force of the rotation preferably retains theeccentric mass sections (and mass couple sections) in substantiallyadjacent positions. When the rotation frequency of the rotating surface20 is at the excitation frequency, the centrifugal force preferablycauses the bearings to slide within the groove, distributing themultiple eccentric mass sections substantially equally about therotational axis 202. The bearings and/or the eccentric mass sections caneach additionally include magnets, disposed in repulsive relation toadjacent magnets, which facilitate eccentric mass separation in responseto the receipt of a system oscillation. In another variation, the masscouple sections rotatably couple along the longitudinal axis of an axleextending from the cam 220 (e.g., mass couple sections are stacked alongthe axle). In another variation, one mass couple section is staticallyconnected to the cam 220 while the remaining mass couple sections arerotatably connected to the cam 220. However, the mass couple sectionscan be otherwise connected to the cam 220.

When the mass couple 260 couples to the cam 220 at the rotational axis202, the mass couple 260 is preferably operable between the coupledmode, wherein the mass couple 260 connects the eccentric mass 240 to thecam 220, and the decoupled mode, wherein the mass couple 260 disconnectsthe eccentric mass 240 from the cam 220. In one variation, the masscouple 260 is a disk located within the lumen defined by an interiorbearing surface of the cam 220, wherein the disk can rotate relative tothe interior bearing surface in the decoupled mode and is coupled to theinterior bearing surface by a friction element in the coupled mode. Themass couple sections are preferably rotatably coupled to the disk, butcan alternatively be disk sections (e.g., concentric circles, arcuatepieces, etc.). The friction element can be a high-friction coating alongthe interior bearing surface, a high-friction coating along the masscouple 260 exterior, a roller or wedge, or any other suitable elementcapable of providing friction between the interior bearing surface andthe mass couple 260. The friction element is preferably selected suchthat the cooperative centrifugal force of the eccentric mass 240 in thecoupled mode applies sufficient force to the mass couple 260 such thatthe friction between the mass couple 260 and the interior bearingsurface retains the mass couple position relative to the cam 220. Thefriction element is preferably selected such that the cooperativecentrifugal force of the eccentric mass sections in a separated ordecoupled mode does not provide enough force for interface friction toretain the mass couple position relative to the cam 220, therebyallowing free mass couple 260 rotation. In another variation, the masscouple 260 is rotatably mounted on an axle extending from the cam 220 bybearings, wherein the mass couple 260 can be statically coupled to thecam 220 by one or more sets of magnets or pistons extending from theadjacent broad faces of the cam 220 and mass couple 260. However, thestatic mass couple connection to the cam 220 to achieve the coupled modecan be selectively controlled by any other suitable passive or activemeans.

The eccentric mass 240 can additionally include a connection mechanismthat functions to couple the multiple sections together. The massconnectors are preferably located on the interfaces of adjacentsections, but can alternatively be located within the section bodies, atthe interfaces of adjacent mass couple sections, or at any othersuitable location. The coupling force of the connection mechanism ispreferably selected such that it is substantially equal to or lower thanthe angular separation force experienced by the individual eccentricmass sections when the system is rotating at the excitation frequency.However, the coupling force can have any other suitable magnitude. Theconnection mechanism can be a mechanical connection (e.g., adhesive,clips, Velcro, etc.) with a separation force substantially equivalent tothe coupling force, a magnetic connection wherein adjacent eccentricmass or mass couple sections include complimentary magnets, or any othersuitable mechanism that can selectively connect adjacent eccentric masssections together.

In one alternative, the eccentric mass 240 is collectively formed by afirst and a second section as shown in FIGS. 3A and 3B (e.g., theeccentric mass 240 is divided radially into two sections), wherein thefirst section is a reflected duplication of the second section. Inoperation, the first and second sections are preferably diametricallyopposed and spin about the axis of rotation of the positioning mechanismwhen the system vibration reaches the resonance frequency of theeccentric mass 240. In a second alternative, the eccentric mass 240 iscollectively formed by a first, second, and third section withsubstantially the same mass, wherein the first, second and thirdsections are preferably substantially evenly distributed about therotational axis 202 when the system rotational speed reaches theresonance frequency of the eccentric mass 240. However, the eccentricmass 240 may be formed from any number of constituent sections in anysuitable configuration. Alternatively, the stabilizing mechanism 300 maybe any other suitable mechanism.

The energy extraction system 10 can additionally include a dampingmechanism that functions to minimize oscillations of the eccentric mass240 within the system. Oscillations of the eccentric mass 240 may resultin eccentric mass excitation, wherein the eccentric mass 240 spinswithin the system instead of remaining substantially static relative toa gravity vector. Oscillations may arise from irregularities in therolling surface (e.g., the road), dynamic unbalance (e.g., due to wheelmass distribution), the pumping pulse (e.g., when the pumping pulseoccurs at an frequency that excites the mass), or may arise from anysuitable mechanism that may generate oscillations of the eccentric mass240.

In a first variation, the damping mechanism includes Dynabeads or otherdynamic balancing mechanisms located within an internal channelencircling the rotational axis 202. In a second variation, the dampingmechanism is a torsional mass-spring system, wherein the resonantvibration period of the mass-spring system is preferably matched to thegravitationally induced resonant frequency of the eccentric massoscillation. The torsion spring is preferably coupled to the cam 220such that the eccentric mass oscillations cause an inertial transfer,which excites the torsional mass-spring system into resonance at a phaseshift that is 180 degrees out of phase with the oscillations of theeccentric mass 240. The torsion spring is preferably coupled between thetorsional mass and the cam 220, but may alternatively be positionedbetween the cam 220 and the mass couple 260, or in any suitableposition.

As a person skilled in the art will recognize from the previous detaileddescription and from the figures and claims, modifications and changescan be made to the preferred embodiments of the invention withoutdeparting from the scope of this invention defined in the followingclaims.

I claim:
 1. An energy extraction system configured to couple to arotating surface, the system comprising: an energy extraction mechanismconfigured to statically couple to the rotating surface, the energyextraction mechanism configured to revolve about a revolution axis; anda counterweight rotatably coupled to the energy extraction mechanismwith the counterweight offset from the revolution axis, thecounterweight operable between a cohesive state and a distributed state,the counterweight configured to switch from the cohesive state to thedistributed state in response to an applied external force, and from thedistributed state to the cohesive state in response to removal of theapplied external force.